1. Field of the Invention
The present invention generally relates to digital photography and, more particularly, to a digital camera with high dynamic range mode of operation.
2. Background Description
High dynamic range (HDR) photography is becoming more popular because it permits the photographer to capture a greater range of tonal detail than the camera is capable of capturing in a single photograph. Sensors for digital cameras have become higher resolution with each new generation of sensor. The increased number of pixels correspondingly means a decrease in the size of the individual pixels for a given sensor size. Unfortunately, the higher resolution of the sensors is often not accompanied by an increase in the luminance range of the sensors. For example, in a landscape where the sky is bright but the foreground is only moderately bright, the photographer must make a determination as to whether the photograph should be properly exposed for the sky, making the foreground quite dark, or properly exposed for the foreground, blowing out all the detail of the sky. One solution has been to use a neutral density gradient filter attached to the lens which, in effect, lowers the exposure of the sky when the foreground is properly exposed. However, this well known approach is limited, and that is the reason for the current interest in HDR photography which, up until recently, had been primarily used in computer generated imagery.
The technique requires the photographer to provide a stable platform for the camera, i.e., a tripod, and take a series of exposures of the same scene, typically three or five exposures, at different exposure values (EVs). It is important that the camera not be moved between the successive exposures since the computer software that will merge the series of photographs requires that the images be aligned. Some of the available computer software provide a limited alignment function to account for any misregistration between images. The computer software maps luminance values at each corresponding pixel of the several images. Examples of current computer software that provides HDR merging of images are Photomatix Pro and Photoshop CS3 and CS4.